A monk may be conveniently defined as a member of a community of men, leading a more or less contemplative life apart from the world, under the vows of poverty, chastity, and obedience, according to a rule characteristic of the particular order to which he belongs. The word monk is not itself a term commonly used in the official language of the Church. It is a popular rather than a scientific designation, but is at the same time very ancient, so much so that its origin cannot be precisely determined. So far as regards the English form of the word, that undoubtedly comes from the Angle-Saxon munuc, which has in turn arisen from the Latin monachus, a mere transliteration of the Greek monachos. This Greek form is commonly believed to be connected with monos, lonely or single, and is suggestive of a life of solitude; but we cannot lose sight of the fact that the word mone, from a different root, seems to have been freely used, e.g. by Palladius, as well as monasterion, in the sense of a religious house (see Butler, "Palladius's Lausiac History" passim). Be this as it may, the Fathers of the fourth century are by no means agreed as to the etymological significance of monachus. St Jerome writes to Heliodorus (P.L., XXII, 350), "Interpret the name monk, it is thine own; what business hast thou in a crowd, thou who art solitary?" St. Augustine on the other hand fastens on the idea of unity (monas) and in his exposition of Ps. cxxxii, extols the appropriateness of the words "Ecce quam bonum et quam jucundum habitare fratres in unum" when chanted in a monastery, because those who are monks should have but one heart and one soul (P.L., XXXVII, 1733). Cassian (P.L., XLIX, 1097) and Pseudo-Dionysius (De Eccl. Hier., vi) seem to have thought monks were so called because they were celibate.

In any case the fact remains that the word monachus in the fourth century was freely used of those consecrated to God, whether they lived as hermits or in communities. So again St. Benedict a little later (c. 535) states at the beginning of his rule that there are four kinds of monks (monachi):

cenobites who live together under a rule or an abbot,

anchorites or hermits, who after long training in the discipline of a community, go forth to lead a life of solitude (and of both of these classed he approves; but also

"sarabites" and

"girovagi" (wandering monks), whom he strongly condemns as men whose religious life is but a pretence, and who do their own without the restraint of obedience.

It is probably due to the fact that the Rule of St. Benedict so constantly describes the brethren as monachi and their residence as monaslerium, that a tradition has arisen according to which these terms in Latin and English (though not so uniformly in the case of the corresponding German and French works) are commonly applied only to those religious bodies which in some measure reproduce the conditions of life contemplated in the old Benedictine Rule. The mendicant friars, e.g. the Dominicans, Franciscans, Carmelites, etc., though they live in community and chant the Divine Office in choir, are not correctly described as monks. Their work of preaching, mixing with their fellow men in the world, soliciting alms, and moving from place to place, is inconsistent with the monastic ideal. The same is to be said of the "clerks regular", like the Jesuits, in whose rule the work of the apostolate is regarded as so important that it is considered incompatible with the obligation of singing office in choir. Again members of the religious congregations of men, which take simple but not solemn vows, are not usually designated as monks. On the other hand it should be noted that in former days a monk, even though he sang office in choir, was not necessarily a priest, the custom in this respect having changed a good deal since medieval times. Besides the Benedictines with their various modifications and offshoots, i.e. the Cluniacs, Cistercians, Trappists etc., the best known orders of monks are the Carthusians, the Premonstratensians, and the Camaldolese. The honorary prefix Dom, and abbreviation of Dominus is given to Benedictines and Carthusians. HEIMBUCHER, Die Orden und Kongregationen (Paderborn, 1907 sqq.); HELYOT, Histoire des Ordres Religieux (Paris, 1743); SCHIEIETZ, Vorgesch. des Monchthums in the Archiv f. kath. Kirchenrecht (Mainz, 1898), 3 sqq. and 305 sqq.